Hi Jase,
You did mean astronomy and not astrology, right?
The Celestron scopes are expensive here because the distributor takes a cut of the profits. We are also a tiny market compared to the US and therefore lack buying power. This is something that is discussed every now and then here.
f/4 is great for deep space objects. But, as that is considered "fast", you need to collimate carefully, as aberrations can show up quite easily.
f/10 and beyond is ideal for planets. A lot of the guys that do hardcore planetary imaging, operate well in excess of f/22.
You can turn a slower scope into a faster scope, through the use of focal reducers. You might want to look at the Hyperstar and Fastar solutions.
Welcome back.
H